Vinkers DJ, Gussekloo J, Stek ML, et al: Temporal relation between depression and cognitive impairment in old age: prospective population based study. BMJ 2004;329:881-3.
The authors studied the temporal relationship between depression and memory loss by prospectively following all 85-year-old inhabitants of Leiden, Netherlands whose baseline mini-mental state exam (MMSE) did not show severe cognitive impairment (score >= 19 points of a total 30 points). At baseline, 37% of the 500 participants were men, 67% had no significant depressive symptoms (score <= 2 points on a geriatric depression scale), and 83% had no serious dementia (score >= 24 on MMSE). Although depressive symptoms and cognitive impairment were significantly correlated on cross-sectional analysis, depressive symptoms at baseline did not predict a more rapid cognitive decline. On the other hand, cognitive impairment at baseline was associated with an accelerated increase of depressive symptoms over the 4 years of follow-up. In this group of community-based elderly persons, impairment of memory or attention preceded the development of depressive symptoms.